On the optical anisotropy of β‐rhombohedral boron

Abstract

The structure model which has been proposed for the ( 3 -rhombohedra1 modification of crystalline boron by Hoard and Hughes (1) is to be assigned to the space group Dw-R&Consequently f3 -rhombohedra1 boron should be uniaxial with the optical axis parallel to the crystallographic c-axis and, because of the inversion center in this space group, no optical activity should appear (cf. e. g. (2, 3)). 5Regarding these considerations the results of Bachan et al. With this set-up in the spectral range from 0.55 to 13 1.1 m no optical rotation could be detected, when the plane of oscillation of the incident light was chosen exactly parallel or perpendicular to the crystallographic c-axis. In the range between 1 and 2 p m the optical rotation within a sample of 1.2 mm thickness was beyond the detection limit of 1' of a precision polarimeter. In the cases i!?llZ and flG the ellipticity of initially plane polarized light is very small ( < 1 ) after having passed the sample and can be easily explained by the considerable structural defects (cf. (5)) of the investigated single crystals (Wacker-Chemie, Munich). 0Reflectivity measurements depending on the crystal orientation (6, 7) have confirmed the existence of linear birefringence expected from the crystal structure.

Optical Anisotropy of β‐Rhombohedral Boron from 0.4 to 16 μm

“…4 and 5 ) . I n the range between absorption edge and lattice vibrations the refractive index well agrees with the results obtained from interferences [7].…”

“…1) is dominated by an additional absorption process being distinctly different for both crystals and both crystal orientations. At higher absorption levels all spectra agree and finally join the results reported in [8], which are included in Fig. 1 and 6 for completion.…”

“…The present investigations yield the optical anisotropy in the visible and near infrared region as supplement to an earlier work on the intrinsic absorption [8]. From symmetry considerations (space group R3m [13]) results that the tensor of the dielectric constant is completely described by the components &lle and &le.…”

Tetragonal Single‐Crystalline Boron Nanowires with Strong Anisotropic Light Scattering Behaviors and Photocurrent Response in Visible‐Light Regime

“…Because the boron has a large refractive index (3.03) at visible regime, its corresponding nanostructures are expected to sustain strong light‐scattering behaviors. In addition, the boron also has birefringence characteristics, which can give rise to strong nonlinear optical properties under ultrafast laser excitation . However, up to now, to the best of our knowledge the studies on the photonic and optoelectronic properties of the boron nanomaterials are remained unexplored.…”